README.md

id	title	brief	article	sdk
867AC718-85E4-4750-9362-CB031EC02D84	Start Activity For Result	In the Hello, Multiscreen Applications guide, we learned how to navigate and pass data from one Activity to the next. This recipe augments the sample application built in the Hello, Multiscreen guide to pass data from from the second Activity back to the starting Activity using StartActivityForResult.	title url Hello, Multiscreen Applications https://developer.xamarin.com/guides/android/getting_started/hello,_multi-screen_applications	title url Android Activity http://developer.android.com/reference/android/app/Activity.html

Recipe

We've learned how to pass data from the first Activity to the second, but what if you want to pass data from the second Activity back to the first? One option is to let Android know that you plan to launch the second Activity with the expectation of getting some result back. We can do with with StartActivityForResult.

In our example, we will pass a greeting string from the second Activity back to the first. Let's begin by launching the designer and adding a few extra elements to our layout. Open up Main.axml and add a label right under the title. We will use this label to display the greeting text sent over from the second Activity. Call this label helloText:

Next, add a button called resultButton. We will use this button to launch the second Activity with StartActivityForResult:

Finally, open up Second.axml and add a button called helloButton:

Next, add the following code to the OnCreate method of the FirstActivity to wire up the resultButton click to launching the second Activity with StartActivityForResult:

var resultButton = FindViewById<Button> (Resource.Id.resultButton);

resultButton.Click += delegate {
  var myIntent = new Intent (this, typeof(SecondActivity));
  StartActivityForResult (myIntent, 0);
};

In SecondActivity, wire up the helloButton in the OnCreate button:

var helloButton = FindViewById<Button> (Resource.Id.helloButton);

helloButton.Click += delegate {
  Intent myIntent = new Intent (this, typeof(FirstActivity));
  myIntent.PutExtra ("greeting", "Hello from the Second Activity!");
  SetResult (Result.Ok, myIntent);
  Finish();
};

Set the data to be sent back to the first Activity with SetResult, passing in the result status and the data (in this case, our Intent). When you're through with passing the data, let Android know you're done by calling Finish.

To handle the result in the first Activity, we will override a method called OnActivityResult. This will listen for our result code and the Intent that we passed into SetResult in the second Activity:

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
  base.OnActivityResult(requestCode, resultCode, data);
  if (resultCode == Result.Ok) {
     var helloLabel = FindViewById<TextView> (Resource.Id.helloLabel);
     helloLabel.Text = data.GetStringExtra("greeting");
  }
}

Finally, we will display the string that we passed to the first Activity as a greeting in the first Activity.